Stress is a fact of life for bacteria, eukaryotic metabolically active cells and any organism in a dynamic environment. Our research focuses on the regulation of SigB, the bacterial general stress response sigma factor and its effects on the oxidative stress response. Bacteria, pathogenic and nonpathogenic, live in complex environments and must monitor their surroundings in order to adapt to the constant changes it faces. Bacillus subtilis accomplishes this by using sensor proteins that sense the environment and proteins that enact changes in gene expression to ultimately alter the physiology of the cell and accommodate the changing conditions. B. subtilis uses the stressosome, a multiprotein complex, to sense its environment and we are interested in asking what are the roles of the individual stressosome proteins? what are the molecular protein interactions that control their activities? and what other signals does the stressosome sense besides physical environmental stress? Our preliminary results suggest the stressosome aids in the protection against oxidative stress. We approach these questions using a combination of genetics, molecular and microbiology techniques.
Students in my lab study the bacterial response to oxidative stress and the role of the general stress Sigma factor SigB in protection against this stress. Student projects range from classical microbial physiology assays to modern molecular techniques to understand the function of the stressosome. Current projects include 1) measuring the role of individual Rsb genes in the stress response by assaying viability after exposure to chemicals that produce oxidative stress such as reactive oxygen, nitrogen and sulfide species, 2) measuring SigB activation after each stress in different mutant backgrounds using reporter assays, 3) measuring the transcriptional response in cells after stress, specifically asking how Rsb genes are regulated at the mRNA and protein levels, and 4) directly assaying the behavior of stressosome proteins and their stress dependent phosphorylation.